/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/MeshNormals.h
Apply rounds of explicit uniform-weighted normal smoothing to the VertexNormals attribute of the given Mesh.
static void SmoothVertexNormals ( [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) & Mesh, int32 SmoothingRounds, double SmoothingAlpha )